Epinephrine-containing neurons in the brain are thought to influence cardiovascular function, pituitary hormone secretion, and physiological responses to stress. The long-term objective of the proposed work is to determine the physiological mechanisms that regulate epinephrine synthesis and release in the central nervous system. The specific aims of this project are to investigate the regulation of phenylethanolamine N-methyl transferase (PNMT), the enzyme that converts norepinephrine to epinephrine, and to determine the relationship between changes in PMNT activity ad epinephrine turnover in subcellular fractions of discrete areas of the hypothalamus and brainstem. The enzymatic properties of each subcellular fraction will be investigated to localize compartments of epinephrine synthesis, and procedures for measurement of PNMT activity in subcellular fractions of hypothalamus will be optimized. Characterization of PNMT activity in the brains of diabetic rats will extend our previous observation that diabetes elevates PNMT activity in the brainstem. Further, the effects of fasting, altered feeding schedules, and changes in steroid hormones on both epinephrine turnover and PNMT activity will be explored. These studies will provide new information on the regulation of PNMT and epinephrine and will provide a platform for further investigations of the molecular regulation of PNMT in the central nervous system.